Optical tape for data storage has the potential for relatively large areal densities. However, data transfer rate is also desirable. Magnetic linear tape addresses transfer rate by simultaneously reading/writing with multiple heads (e.g., such as thirty-two heads). The heads are constructed on micron scales using semiconductor technology such that the heads may be laterally arrayed at low spacing (e.g., such as 90 μm).
Optical pickup units are used in optical data tape storage machines to read and write data on an optical tape. An optical pickup unit (OPU) typically includes a laser, a lens, lateral and focusing actuators for the lens, optical paths, and mounting structures. An OPU is considerably more bulky than a magnetic head.
A single OPU may be used in disk products having adequate room laterally (i.e., radially) for the OPU components. The use of multiple OPUs is required to meet optical tape data transfer requirements. In prototype drives, multiple OPUs have been arrayed longitudinally along the tape path. The multiple OPU longitudinal arrangement is limited by or limits the following. The available drive space for the tape path and OPU footprints is limited. The tape path layout/design options are limited. The lateral tape motion (LTM) is well controlled only in relatively small portion(s) along the length of the tape path. The OPUs that might be designed for the longitudinal arrays would have a narrow footprint, which limits space for mounting and alignment features. Lasers in each of the OPUs generate heat during operation and cause their temperature to rise. Operating at high temperatures contributes to premature degradation of the lasers and impact the reliability of the drive. Having many lasers mounted closely together creates a challenge to keep the lasers from getting excessively warm and degrading their lifetime. Hence, there is limited space for multiple OPUs and limited means for keeping them cool.